Along with the development of communications and the proliferation of multimedia technology, a variety of large-capacity transmission techniques have been adopted for wireless communication systems. Although wireless capacity can be increased by allocating more frequency resources, there is a limit to allocating more frequency resources to multiple users due to limited frequency resources. One approach to efficient utilization of the limited frequency resources is to scale down the sizes of cells. In a smaller cell, a Base Station (BS) may service a reduced number of users and thus may allocate more frequency resources to the users. A large-capacity service with better quality can be provided to multiple users by reducing the sizes of cells.
Femtocells installed in houses and offices are a recent extensive research area. A femtocell is an ultra-small mobile communication BS deployed for indoor use such as a house or an office. While a femtocell is regarded as a similar type to a picocell, the former is more advanced than the latter in terms of functions. The femtocell is connected to an Internet Protocol (IP) network available in the home or office and provides a mobile communication service by accessing the Core Network (CN) of a mobile communication system through the IP network. For example, the femtocell is connected to the CN of the mobile communication system via a Digital Subscriber Line (DSL). In the mobile communication system, a user may receive a service from a legacy macrocell outdoors and from a femtocell indoors. Femtocells are complementary to legacy macrocells whose services get poor within buildings, thereby improving indoor coverage of the mobile communication system. Since the femtocells serve only specified users, they can provide high-quality voice and data services to the users. Furthermore, the femtocells can provide new services that are not available from the legacy macrocells. The widespread use of femtocells is a driving force behind Fixed-Mobile Convergence (FMC) and reduces industrial cost.
A femtocell is personal communication equipment that an individual installs in his or her house or an office, accessible to specific users only. Once it is powered on, communication equipment installed in a house or an office is typically kept powered-on even though it is not in use. To reduce interference between a femtocell and a macrocell, the femtocell may operate in a different frequency band from that of a macrocell. When a User Equipment (UE) is located in the service area of a femtocell inaccessible to the UE, the UE should use a frequency band other than a frequency band allocated to the femtocell, irrespective of whether the frequency band of the femtocell is used or unused. The resulting possible limit to the use of radio resources for UEs located near to the femtocell may lead to inefficient use of limited radio resources.
Accordingly, there exists a need for a method for efficiently operating a femtocell.